Hello,
I read the topic KOrganizer Calendar Data Location but didn’t get lucky.
I was on KUbuntu 26.04 and I switched to CachyOS.
I started with a fresh empty user folder and I’m in the process of reconstruct my KDE desktop.
I use three nextcloud calendars from my own nextcloud server on a RPi.
I copied those files and folders from my old /home/user folder to my new /home/user folder :
.local/share/apps/korganizer/
.local/share/{akonadi,akonadi-davgroupware,akonadi_maildir_resource_0,akonadi_migration_agent}
.config/{konadi,akonadi_birthdays_resourcerc,akonadi_contacts_resource_0rc,akonadi-firstrunrc,akonadi_ical_resource_0rc,akonadi_indexing_agentrc,akonadi_maildir_resource_0rc,akonadi-migrationrc}
.config/korganizerrc
Then I did sudo pacman -S korganizer kdepim-addons that installed numerous dependencies, like KOrganizer.
AND, now I can view my calendars in my clock in the taskbar ! \o/
Thank you kde-pim, I suppose.
But… nothing in KOrganizer ! 
To be honest, I use mainly Thunderbird and my smartphone with those calendars, so It’s not a deal-breaker ; but I fear a problem might occur in the long term.
What do you think and do you know how I should have proceeded ?
Thank you.
When you partition your drive(s), it’s best to create a separate /home partition.
As for the filesystem, there’s no reason to use Btrfs (it’s not a backup tool); choose EXT4 or XFS instead.
If you switch distribution, do not reformat your /home directory, only the root directory (/).
That way, you won’t lose your data or your personal configuration.
And of course, back up your /home directory to an external drive or cloud storage (Rsync and Borg are handy and reliable).
Hello,
In fact, I have a /home partition, for my KUbuntus (26.04 and 24.04) and now I have a new one for CachyOS.
Why ?
Because :
-
I wasn’t confident in my skills to manage CachyOS, so I dual boot with KUbuntu for now (not for long, I hope) => I tried KDE Neon once and it was a disaster despite years of KUbuntu’s “mastering”, so I decided to be more prepared, this time and start with a fresh user home directory
-
the new /home is in a nvme SSD vastly faster than the old one
But, As I suspected in my OP, I have a problem => I can’t change the color the calendar is displayed in the taskbar clock ! 
I need to manage my calendars with another tool.
I think it would be more simple to simply add them from scratch as they are remote calendars => I didn’t lost any local calendar.
But before that, I will wait a bit more if someone would provide the missing information for my “salvation”. 
I deleted the old configuration, and added the nextcloud agendas.
It took me 1 minute and I should have done that in the first place, but honestly, I’m only half-happy. I really wanted to restore the data from my old user directory.
It is what it is.
Thank you for your time.